How to Calculate Thermal Conductivity of PCB?

Many mass-manufactured boards will be placed on FR4, which has very low conductivity compared to a number of alternative materials. The thermal conductivity of a PCB substrate is often considered an afterthought. There are a number of design tradeoffs that should be considered when choosing a substrate that spans beyond thermal conductivity, and you might be better off using a substrate with low thermal conductivity alongside some passive or active cooling methods. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } In this article, we will talk about thermal conductivity of PCB. If you are going to learn more PCB knowledge, please check and read the content we provide for more information. Why thermal conductivity is important to PCB? Heat management is crucial for PCB performance, reliability, and longevity. Inadequate heat management may lead to delamination, damage, or device failure (Figure 2). Thermal conductivity plays a vital role in heat management, and thus it is a key parameter for PCB design. The C-Therm Trident thermal conductivity platform is a useful tool in obtaining rapid, precise, and accurate measurements of PCB component thermal conductivity. The “hot” topic in PCB design is high-speed signal integrity. But on another front, PCB designers may be interested in how hot (literally) an individual PCB trace becomes. Trace temperature is directly related to reliability. In the extreme, a trace that is too hot can melt the solder or cause a board to delaminate. But generally we want trace temperatures to be a lot lower than that. The trace reaches a stable temperature when the heating of the trace equals the cooling of the trace. The heating of the trace is caused by the I2R (power) drop across the trace. It is only in the last 10 years that the industry has recognized the importance of the dielectric in the trace cooling process. How does thermal conductivity influence PCB? Choosing a substrate with an appropriate thermal conductivity is one of many important aspects of PCB design. Thermal management in PCBs becomes particularly important in smaller boards with active components that switch at high speed. It is also important in boards that will carry high current as resistive losses in a trace will generate heat, which then transfers into the substrate. If you know that your board will generate a large amount of heat during operation, or if your board will operate in a high-temperature environment, then you may need to use a substrate with higher thermal conductivity. You may also need to implement passive cooling, active cooling, or both in order to keep the temperature of important components within their safe operating range. It is also important. Component Size As components become smaller, so does the ability to dissipate heat naturally. For example, a MOSFET with a SOT-23 package will have less area for its heat pad than one in TO-220. Therefore, the size of components mounted on a PCB will influence its ability to propagate heat. Thermal Vias Thermal vias are holes intentionally placed to dissipate heat off a component. It’s kind of like providing more opportunity for the steam to escape from your porridge instead of trapping it in a container. So, naturally, this means that the more thermal vias there are in an area, the more they will increase the effective thermal conductivity of a PCB. Internal Layers The presence of internal copper layers can also change the rate and direction of heat dissipation. The thermal conductivity for copper is 355 W/m-K, while FR-4 is 0.25 m-K. With multiple inner-layers of copper, the effective thermal conductivity of the PCB would decrease. Of course, the presence of thermal vias could help to move the heat to the inner layers more efficiently. How to calculate thermal conductivity of PCB? As a fundamental property of any material, thermal conductivity defines the heat flux between hot and cold regions in your PCB. The thermal conductivity of your substrate material can be found in material datasheets. However, once you have an idea of your stackup and copper weight in your layout, you will want to calculate the effective thermal conductivity of your substrate. Formulas for calculating this directly vary depending on who you ask, although there are a number of lumped models in the literature. The simplest method is to use a weighted average based on the volume of copper and substrate material in your PCB: Effective thermal conductivity estimation Effective thermal conductivity estimate based on a volume weighted average of your PCB material parameters The above equation shows a simple volume weighted average for calculating the effective thermal conductivity, where “s” indicates the substrate and “c” indicates copper. However, this is just a rough estimate, and you’ll get much more accurate results if you use a specialized 3D multiphysics simulator. Once you’ve determined the effective thermal conductivity of your PCB, you’re ready to calculate the thermal resistance in your board, which will give you some idea of how heat will transfer through your stackup. What is effective thermal conductivity of PCB? Effective thermal conductivity refers to the ability of a material to conduct and transfer heat. When we’re talking specifically about a PCB’s effective thermal conductivity, we’re talking about how well the PCB can move the heat generated from its components to its surrounding area. Effective thermal conductivity is represented by the symbol and values are expressed in W/m•K. In PCB design, effective thermal conductivity is an important aspect used in thermal modeling and analysis because it allows engineers to predict how well a populated PCB would conduct heat based on specific assumptions and models. With electronic modules continuing to shrink in size, it is a parameter that deserves attention amongst designers.

PCB Knowledge ⋅ 08/21/2021 09:24

PCB DFM Guidelines

Design for manufacturing (DFM) is the practice of optimizing the engineering workflow of producing an electronic device. With this much competition, it isn’t only the latest and greatest designs that will win the day, it is also which circuit boards can be built quickly, efficiently, and for the lowest manufacturing costs. To achieve that goal requires that today’s PCB engineers be well versed in design for manufacturing, or DFM, techniques and methods. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } In this article, we will analyze the DFM in PCB manufacturing process. Please check and read the content we prepare to learn more professional knowledge about it. Why DFM in PCB is important? In order to avoid all of these problems, PCB designers need to incorporate good DFM practices during their initial circuit board design. This will reduce the need for changes later on, and preserve the layout of sensitive circuitry that is fine-tuned for performance in the prototype. The first step in understanding DFM in circuit board design is to be aware of the manufacturing problems that can happen without them. When a prototype circuit board is first being developed, the focus is usually on the functionality rather than the buildability of the board. As such the component placement on the board may not be optimized for assembly, which may result in higher assembly costs. Even during limited production runs for prototyping, a lot of manufacturing costs can be saved by designing the board for automated manufacturing. These problems are magnified however when the board is ready to be moved into its production phase. Components that are not optimized for manufacturing will have to be re-positioned to avoid the necessity of manual assembly. Another problem is with components that weren’t selected for long-term production. If their price is too high or their availability is limited, the board will encounter additional manufacturing problems. What are the factors of DFM in PCB? If a PCB is performing appropriately and the design engineer is also satisfied with it. Then why DFM checks for it? There are various reasons: cost of final PCB, design layout, and chances of future design failure. · Theoretically, in cost terms, PCB designs submitted without DFM checks are less expensive than the designs with DFM checks. But it is better to pay a little extra so that the manufacturer could ensure whether the design is manufacturable or not. · To sustain a PCB layout with DFM issues, CAM engineers edit the data to meet the design requirements. This is one primary reason that introduces signal integrity issues and EMI/EMC issues. · PCBs assembled and tested efficiently, still fail. The main reason is that the design data still contained the DFM errors that were resolved in the prototype but were not implemented during the production. What are the guidelines of DFM in PCB？ To get the best results in a prototype build, you need to choose a CM that is fully versed in and ready to help you with DFM requirements. Not all CMs are set up for it, and in the case of CMs, they might not have the capabilities to support any DFM engineering at all. For success, make sure to work with a CM that: · Completely understands all DFM requirements and will work with you during the design phase to help you incorporate those requirements. · Has the engineering staff and facilities to review your design, recommend DFM changes, and even make those changes, if that is in your best interest. · Has the manufacturing proficiency to work with prototype designs that have DFM problems in them to get your product built correctly and returned to you quickly. · Select the right manufacturer and involve them up front: Different manufacturers can have strengths and weaknesses just as any business can. Ensure that you have selected the best manufacturer for building your PCB. Once you have made that choice, it is important to also involve them as early as possible with your design. This way you can design your PCB to their DFM rules, instead of making changes later. · Consider the board form factor: The more complex your board shape is, the more involved it will be for the fab vendor to work with. This also includes cutouts and slots in the board. By keeping the board shape as rectangular as possible, you will save money on your fabrication costs. · Keep the components as uniform as possible: A PCB that has many different-sized components on it will slow down the manufacturing process. Each different component size requires different setups for the assembly line, so reduce these to reduce manufacturing time and expense. How to use PCB DFM Guidelines? Despite how important PCB DFM guidelines are, there are no generic guidelines that apply to every single type of PCB design. This means that designers must often use their best judgment concerning which guidelines to follow. Most of the time, however, designers don’t have to guess, since there are some guidelines that work well for most PCB types. For example, a designer can be confident that a PCB with copper traces should be checked for disconnected traces and trace violations, regardless of that PCB’s application. On the other hand, high-speed digital PCBs have DFM guidelines that don’t apply to other PCB types. If a PCB manufacturer recommends following certain DFM guidelines, designers should be ready to perform those checks.

PCB Knowledge ⋅ 08/19/2021 17:23

EMI PCB Design Guidelines

Digital circuits are getting faster and more powerful each year, and as a result, it's more important than ever to utilize proper design techniques and materials to reduce electromagnetic interference (EMI) in our PCB designs. Poor planning can lead to increased and unnecessary radiation, as well as reduced system immunity, which can wreak havoc on our devices. In this article, we will tell you everything about the EMI PCB design details. Please check and read the content we prepare below for more PCB knowledge. Let’s go!If you want to order PCB product, please check and custom your order online. How to optimize EMI PCB Design? As explained in the previous section, the likelihood that your board or the system on which it operates contains components or equipment that can be classified as radiators is very high. Besides, unless your circuit board is a stand-alone device, the power supply is directly or indirectly connected to the power supply, which is also a common source of electromagnetic interference. The purpose of the EMI filter is to reduce the interference introduced into your board from this source. EMI filters can be designed from a single component to a complex network with dedicated circuits to mitigate common-mode and different-mode noise. Some basic types of EMI filter design and how to use them are listed below. Once you have decided on a basic design, it will be necessary to optimize it according to the performance specifications of your circuit and/or board. For example, if your EMI filter is designed to drive other circuits or boards, you may be required to add additional filter elements for isolation, smoothing, or electrical parameter constraints (for example, fixed voltage or current). The extent to which you can meet these circuit requirements depends on the capabilities and capabilities of the PCB design and analysis tools available. What are the guidelines of EMI PCB design? As is the case for all circuit board designs, following good EMI filter PCB layout guidelines is essential for manufacturability. Again, the best design requires the adoption of the proper perspective. 2-D PCB Design Perspective When laying out your board, the first considerations are the locations for component footprints—whether from your design package’s library or uploaded from an external source—trace routing, spacing, or board edge clearance. · Ensure that pads and component libraries are matched.· Maximize spacing between adjacent elements—pads, traces, and annular rings—to minimize interference.· Partition components according to signal types.· Assure that trace widths and sizes are sufficient for the current capacities required.· Ensure that impedance matching is instituted where necessary for differential routing, maximum power transfer, etc.· Follow board clearance rules to facilitate depanelization.· Use shielding for high radiation devices.· Make good use of the silkscreen for component polarities and reference indicators to aid assembly. How to reduce EMI in PCB design? Ground planeThe ground plane is in many ways your first line of defense against the kind of noise produced by EMI, because circuits require at least a floating ground in order to work. In a PCB board, the ground plane is there to provide a 0 volt reference line to the power supply ground terminal for the return path of a circuit. Unlike the basin, however, when “ripples” are made, noise is produced, dipoles can form and the entire board can become an antenna. This is why the ground plane, that copper foil layer in your PCB, takes up as much of the cross-sectional area of the board as possible. Reducing EMI across your board starts with how effectively you utilize the ground plane. Trace layoutTraces are conductive paths on a board, which contain flowing electrons while a circuit is active—that means they are just a bend or cross away from creating a fully radiating antenna. Common best practices for trace layout include: · Avoid sharp right-angle bends. Capacitance increases in the 45° corner region changing the characteristic impedance and leading to reflections. This can be mitigated by rounding right angles.· Keep your signals separate. Keep high speed traces (e.g. clock signals) separate from low speed signals, and analog signals separate from digital signals.· Keep return paths short.· Route differential traces as close as possible. This increases the coupling factor, bringing influenced noise into the common mode which is less problematic for a differential input stage.· Use vias wisely. Vias are necessary because they let you take advantage of multiple layers in your boards when routing. Designers must be aware that they add their own inductance and capacitance effects to the mix, and reflections can occur from a change in characteristic impedance.· Avoid using vias in differential traces. If you must, use an oval anti-pad shared by the two vias to reduce parasitic capacitance.Wanna know PCB knowledge? 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PCB Knowledge ⋅ 08/17/2021 17:25

PCI Express PCB Layout Guidelines

PCI is a popular connection interface used for attaching computer peripherals such as RAM, ethernet, and network cards, I/O cards to a motherboard. It was introduced in 1992 with the aim of supporting complex data transfers and evolved its purpose way beyond the same. The PCI bus was made to be available in 32-bit and 64-bit versions. The PCI technology has undergone various updates to evolve into PCI Express which is still under development.、 In this passage, we will tell you everything about PCI Express and please check and read our content for more professional knowledge.If you want to order PCB product, please check and custom your order online. What is the working principle of PCI Express? PCI Express is a serial connection that works more as a network than as a bus. Instead of one bus handling data from various sources, it includes a switch controlling various point-to-point serial connections. Such connections will spread outward from the switch leading to the devices where the data is required to go. As each device has its own dedicated connection, devices no longer share bandwidth as they do on a conventional bus. What is the evolution of PCI? The PCI specification was utilized by the computer industry from 1992 to 2004 as the primary local bus system within a computer. It standardized how PCI expansion cards ranging from a network card to a modem can be self-installed and exchange information with the CPU. CPU processor frequencies rose from 66MHz in 1993 to well over 3GHz in 2003. The existing PCI bandwidth had trouble keeping up with the I/O processing capabilities of the new processors which is what led to the development of PCI Express spec. From 2004 Intel introduced its PCI express spec which kept the core of PCI’s software infrastructure and wholly replaced the hardware infrastructure that could handle higher I/O requirements of processors. PCI had parallel interconnect whereas the new PCI Express has a serial point-to-point interconnect capable of high bandwidth transfers. What are the guidelines of PCI Express PCB Layout? Given are some PCI Express layout and routing guidelines that enable efficient design. Trace routing specificationsWhen compared to most high-speed devices available, PCIe generations permit longer trace in their layout routing specs. Every generation comes with its own specifications on impedance and maximum trace lengths for varying data transfer rates. These should be closely followed to obtain the required performance. The exact routing specifications will depend on which PCIe generation you are utilizing for your design. Trace lengths in Gen 1 and Gen 2 both let RX (received) and TX (transmitted) signal traces reach up to 21 inches in length. When it comes to Gen 3, trace lengths can only go up to 14 inches on signal trace PCIe planes. While each TX trace pair can have only two vias, RX pairs can include up to four vias to maintain impedance within the required specification. A COM Express carrier board allows for trace lengths of up to 9 inches for Gen 1 and 2 when the traces are being sent to a PCIe slot. The tolerance for differential impedance values also differs among the various PCIe generations and bus standards. The values may be different for each bus and generation combination, but they can be found in the COMCDG Rev. 2.0 specification. When keeping the impedance of microstrip traces within specified tolerances, you need to use PCB design software to include controlled impedance routing features. The interactive routing tool in the software will ensure your traces are spread out with the right spacing and geometry. Stack-up and groundingStandard PCIe boards incorporate a 4-layer stack-up with two interior power planes and two signal layers on each surface. Each power layer can be brought to varying bias levels based on device requirements. Other designs for PCIe boards go for a 6-layer stack-up with two signal layers that run between two power layers. In another scenario, one of the power planes can be replaced with a ground plane. In both cases, you can achieve better immunity to EMI by routing signal traces on the inner layers. You can even route traces with varying data rates on different layers. For instance, in a mixed-signal board such as the ones in a WiFi device on a PCIe card, you can route digital traces on the outer layers and the RF traces on the inner layers. The ground/power planes will effectively block noise from reaching the sensitive analog signal traces. Regardless of the stack-up used, you will need to meet the overall board thickness standard of 1.57 mm or 1 mm for PCIe Mini. You will also need to consider standard high-speed design techniques as the Gen 1 of PCIe operates at 2.5 GHz clock speed with future generations increasing in speed. PCI differential pair routingRouting around obstructions and component placement and via placement on a PCIe board is really important. There needs symmetric routing to pins, pads, and components along with the BGA breakout routing. Differential pairs need to be tightly coupled throughout their entire length, with variations in one trace due to vias, pads, or components being mirrored in the other trace. This ensures crosstalk is minimized throughout the differential pair length. Similar practices need to be applied while routing BGA breakouts or breakouts from other components. As the performance requirements of high-speed PCB design continue to increase, it becomes critical to ensure that your design meets PCIe layout routing specifications. PCB board manufacture for PCI requires a great deal of expertise and experience that only a few manufacturers can provide.Wanna know PCB knowledge? Check and read for more.

PCB Knowledge ⋅ 08/16/2021 17:35

Parasitic Capacitance in PCB

Parasitic capacitance or stray capacitance is the result of a virtual capacitor formed between two traces separated by a dielectric. It occurs due to the potential difference generated when the current-carrying traces run in close proximity. To learn more, read the role of trace current capacity in PCB design. This effect is even possible if the conductors are appropriately insulated. It is not possible to avoid parasitic capacitance since no electrical circuit is ideal. In this passage, we provide all about parasitic capacitance in PCB please check and read the content below.If you want to order PCB product, please check and custom your order online. How to calculate parasitic capacitance in PCB? Parasitic capacitance is an inherent property of the conductors. It is the storage of per unit change in electric potential. The parasitic capacitance is calculated as C= q/v. Where C is the capacitance in farads, v is the voltage in volts, and q is the charge in coulombs. · For a constant electrical signal that does not change over time, dv/dt = 0 which means, no change in potential; hence i =0.· If there is a capacitor in the circuit loop, dv/dt will converge to a fixed value, i.e., change in potential, resulting in a current flow; hence i ≠ 0. Trace capacitance calculationThe capacitance of a parallel plate capacitor is given by C= (kA/11.3d)pF. Where C is capacitance, A is the plate area in cm2, k is the relative dielectric constant of board material, and d is the distance between the plates in cm. What is the effect of parasitic capacitance in PCB? The parasitic capacitance effect is a matter of concern in high-frequency circuit boards. While operating at low frequencies, parasitic elements can be ignored since they do not really impact system functionality. Every pad in a circuit board has its parasitic capacitance, and every trace has parasitic inductance. Pads also add their parasitic resistance that stimulates IR losses. Parasitic capacitance can exist between conductors on PCBs, bare boards, PCBAs, assembled boards, and within component packages, especially surface mount devices (SMDs). Since intrinsic capacitor plates have a potential difference, there is a chance of current flow. It does not matter whether the charges are stored between the capacitor plates; the current will not flow until there is a potential difference. As soon as this potential difference increases, a corresponding decrease in electron flow towards the load can be observed for the desired signal path that negatively impacts signal integrity. What are the differences between parasitic capacitance and stray capacitance? The term stray capacitance is often used interchangeably with parasitic capacitance. However, parasitic capacitance accounts for the fact that it will hamper the circuit operation, while stray capacitance accounts for how unwanted capacitance is introduced. What is stray capacitance?Stray capacitance doesn’t always get induced due to the virtual capacitance formed between two PCB conductors but also due to the effect of the surrounding environment. Hence, it is termed as stray capacitance. What is parasitic resistance in a PCB?Parasitic resistance exists in series along traces or as a shunt between the conductive elements. What is parasitic inductance in a PCB?Parasitic inductance exists along a trace and exhibits the behavior of storing and dissipating electrical energy, like an actual inductor. All conductors are inductive, and at high frequencies, the inductance of even relatively short pieces of wire or PCB traces may be important. Where R is the wire radius, and L is the length. How to find the inductance of a PCB trace?Trace inductance increases with trace length and lack of ground plane. What are the causes of parasitic resistance in PCB? At high-frequency, current flow in a circuit board is affected by the parasitic capacitance. Since capacitors are tend to become conductors when frequency increases. Note that when frequency increases, the capacitor will act as a resistor of very small value (approaches to a short circuit), resulting in excessive current flow. Zc = 1/2πfc ; fc = 1/ωc therefore, as frequency increases, Zc also increases. Parasitic capacitance can give you chills during high-frequency operation since a capacitor acts like a wire at an infinite frequency. This is the reason why it can accidentally connect the reference plane of any PCB board to the chassis. Parasitic capacitance effects could be crosstalk and noise, undesirable feedback from the output, and the formation of resonant circuits. So, it is essential to give attention to the overall PCB design, specifically to the layout. A good layout should take utmost care while placing a conductive body by the side of another conductive body. Parasitic elements include inductors formed by package leads, long traces, pad-to-ground, pad to power plane, and pad to trace capacitors, including interactions with vias, etc. Understand parasitic elements as parasites, a threat to your circuit performance.Wanna know PCB knowledge? Check and read for more.

PCB Knowledge ⋅ 08/16/2021 17:30

PCB laser drilling process

When using HDI technology for PCB designing, plenty of microvias are included. These microvias that appear to be blind structures are small in size and require precise controlled depth drilling. This precision can only be achieved using lasers. In this passage, we will focus on the PCB laser drilling topic and if you are going to learn more knowledge please check and read the content below. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } What are the advantages of PCB laser drilling? The advantages of using lasers are listed below: · Non-contact process: Laser drilling is a non-contact process and hence the damage induced on the material by drilling vibration is eliminated. · Precise control: We can control the beam intensity, heat output, and duration of the laser beam. This helps to create different hole shapes and offers high accuracy. · High aspect ratio: One of the most important parameters of a drilled hole on a circuit board is the aspect ratio. It is the ratio between the drilled depth and the diameter of the hole. Since lasers can create holes with very small diameters, they provide a high aspect ratio. A typical microvia has an aspect ratio of 0.75:1. · Multi-tasking: Laser machines used for drilling can also be used for other manufacturing processes like welding, cutting, etc. Lasers can drill 2.5 to 3-mil vias on a thin flat glass reinforcement. In the case of an unreinforced dielectric (with no glass), it is possible to drill 1-mil vias using lasers. Hence, laser drilling is recommended for drilling microvias. What are the methods of PCB laser drilling? Single-pulse/shot laser drilling As the name suggests, in single-pulse laser drilling, a single shot of laser beam is fired at the material to create the required hole. In this method, both the source of the laser and the work material is kept static. Percussion laser drilling In percussion drilling, a series of laser pulses are shot at the work material repeatedly. During this process, there is no relative motion between the laser beam and the workpiece. This form of laser drilling effectively creates deeper and precise holes with smaller diameters as compared to single-shot laser drilling. Trepanning Trepanning is the process in which a laser beam is guided around a predefined locus. This locus is the center of the via to be drilled. It is used in situations where the diameter of the via to be cut is larger than the laser beam diameter. The accuracy of the via is determined by the movement of the beam. Helical laser drilling Helical laser drilling is a method in which the laser beam follows a helical path for movement while rotating about its own axis with respect to the workpiece. A dove prism controls the movement of the laser beam. What are the considerations of PCB laser drilling? During laser drilling, there are a few aspects regarding the circuit board that should be considered. Given below are two of the important ones. Non-homogeneity of the stack-up The non-homogeneity of the PCB materials used in the stack-up is the main consideration while using lasers. Different materials absorb energy at different rates. For example, FR4 resin absorbs light energy at the same rate as the glass fibers and leaves a clean hole. BT epoxy resin vaporizes at a rate faster than glass and hence leaves glass fibers in the hole. In situations like these, obtaining complete accuracy with lasers becomes difficult. Therefore, it is recommended to keep the homogeneity of the multilayer PCB stack-up as much as possible. If we use materials that have different optical and thermal properties, the way the laser beams react with them will also be different, leading to inaccurate drilling. The thickness of copper The minimum thickness of the target copper layer should be twice the thickness of the top copper layer to be penetrated. Apart from a few challenges that may arise, we can surely say that lasers are the best choice to create microvias in PCBs. Given the ever-increasing demand for reducing the board size and increasing the wiring density, laser-drilled microvias are crucial in PCB manufacturing. Creating diminished holes with extreme accuracy without affecting the integrity of the board is a difficult task. Laser drilling is the best way to manufacture such compact boards.

PCB Knowledge ⋅ 08/16/2021 09:52

PCB Design Basics Tutorial

Since PCB design is a very important process during the PCB manufacturing. It involves setting up the board parameters, determining its outline, routing the components, and generating the production documents. It is necessary to know the basic knowledge of it. Please check and read the content we prepare for you below. What are the PCB design basics? While designing a new PCB, it is necessary to adhere to design basics. If neglected, it will result in a poor board design that will be very difficult to manufacture. Therefore, it is necessary to pay attention to the following concepts: PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } Choose appropriate components and package sizes As a board designer, you should thoroughly study the BOM and examine the parts that go into the design. When there is sufficient space on the board, you may opt for larger components for resistors and capacitors. It is beneficial to use a 0603 or 0805 size capacitor/resistor instead of a 0402/0201. Select the smaller package version of the component if you have spacing issues. Moreover, choose your appropriate component and package based on the required current, voltage, and frequency. Smaller components are manufactured by various vendors. It allows designers to choose alternate parts without modifying the schematic or layout, providing a timely solution for components that are not in stock. Furthermore, it is crucial to decide the appropriate size of the package during the PCB design phase. It is recommended to choose smaller packages only when necessary; otherwise, choose larger packages. Using too many small component packages can create issues during circuit board assembly, which leads to difficulties during cleaning and reworking. Avoid long lead-time components The unavailability of components can cause considerable delays. So, it is better to check the availability while confirming component spacing. If your component has a long lead-time, order it immediately. It can be beneficial to have alternate components with the same footprint. Assembly vendors can also procure the widely available parts so that every component will be readily available when it is time to assemble the boards. Schematic checks A schematic is a well-structured circuit diagram that represents the electrical connections between various electronic components. Schematic design basics often get ignored. Make sure you verify the following: · Verification of pin numbering and labels in component symbols · A polarity check for all the polarized components · Overlapping labels and Pins · Ensuring the base, collector, and emitter pins according to the schematic symbols, datasheet, and footprint package · Validation of the component value, location, and reference designators · Descriptions of the schematic symbols · Off-page connectors · Checking the inter-sheet reference · Decoupling capacitor check for all ICs, ground pin separation according to the signal type (analog, digital, signal, ground) · Netlist check for design correctness and wrong connections · Add test points to all important signals · Test points are required to check the electrical conductivity of the board. It is necessary to add test points for all important signals to facilitate electrical tests (E-test) and in-circuit tests (ICT). Keep an eye on the following: Board side: If possible, all test points should be located on the same side of the board to facilitate testing. Minimum test point distance: The minimum distance between test points is 0.100 inches. It maximizes test effectiveness. Test point distribution: Distributing test points evenly on a circuit board makes testing easier with multiple probes. Area for taller components: Designating the area for taller components can streamline the testing. Manufacturing tolerances: Make sure to consider manufacturing tolerances while designing a layout to accommodate a space for test points. Make sure your BOM is up to date while designing A BOM is a detailed list of all the components required to produce a product. Keep your BOM up to date while designing, and if you make any changes to your design, ensure you have also implemented those changes in your bill of materials. For example, if you change the part number in the schematic, update the BOM as well. Before you validate your BOM file, ensure that all the active parts are included in it. The parts should be validated with respect to the following fields: · Serial number · Part description · Designators matching the schematic · Quantity of the parts · MPN · VPN · DNI (do not install) components Stack-up preparation in PCB design Stack-up is an important attribute in the basics of multilayer PCB design. It defines the structure of a multilayer circuit board in a sequential manner. Stack-up provides information about the material thickness and copper weights that are vital for circuit board manufacturing. When boards are precisely stacked, electromagnetic emissions and crosstalk are reduced, and the signal integrity is improved. Know your board’s mechanical constraints, which include board thickness and component height. It is important to know the controlled impedance requirements, including the number of differential pairs, as it will impact the number of layers in your board. The routing density of the circuit board will also impact the number of layers. Choose a PCB material based on the fastest rise time. Verify the manufacturability of your stack-up using our free Stack-up Planner. The following parameters are necessary for the planner: · The PCB material (FR4, I-Speed, Rogers, etc.) depends on the frequency requirements and environment. · Layers including signal and power layers. · Impedance requirements such as 50Ω single-ended, 90Ω differential, or 100Ω differential · Copper thickness (½ or 1 or 2 ounces) Carefully inspect your footprint development Schematic, complete BOM, and stack-up are the backbone of your circuit board. It is easier to create footprints for some components when they come in standardized packages. In most cases, the footprints of standard packages are available in the software’s library (Altium Designer, Allegro, etc.). Otherwise, you will have to create it based on the datasheet of the component. Confirm library components match the recommended land pattern provided in the datasheet. After designing your footprint, do a quality check. Mark your component orientation. Footprints must be checked for top and bottom views, pin pitch, and height. Ensuring the accuracy of your footprint as per the land pattern will eliminate issues during assembly. Placement of components Once the mechanics of the board have been finalized, next is placing components. The proper component placement on a PCB leads to better performance and signal quality. It begins with placing the parts which are at the specified locations according to the design requirements. These components usually consist of connectors and their associated parts. Following that, the main components such as the CPU, memory, and analog circuits will be placed in their proper positions. The third step involves placing auxiliary components such as crystals, decoupling capacitors, and series resistors.

PCB Knowledge ⋅ 08/12/2021 17:13

Decoupling Capacitor Placement PCB

Do you know what is decoupling capacitor in PCB? In this article, we will provide you everything about decoupling capacitor in PCB, please check the content we prepare below to learn more information. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } What is decoupling capacitor? In the strictest sense, there isn’t a specific component that’s defined as a decoupling capacitor. Rather, the term decoupling capacitor refers to the function of a capacitor in an electronic circuit. A decoupling capacitor is one that stabilizes the voltage on the power supply plane. In any design that involves semiconductor ICs, you’ll always need decoupling capacitors. That’s because the voltage supplied to the components is far from ideal. Unlike the perfect horizontal line depicted in theory, voltage readings in real-life applications tend to fluctuate even if you’ve got the cleanest power supply. The decoupling function as reservoir and it acts in two ways to stabilize the voltage. When the voltage increases above the rated value, the decoupling capacitor absorbs the excessive charges. Meanwhile, the decoupling capacitor releases the charges when the voltage drops to ensure the supply is stable. Often, you’ll need at least two coupling capacitors of different values to stabilize the voltage supplied to a component’s VDD pin. A capacitor in the range of 10 uF acts as a larger buffer to smoothen low-frequency fluctuations. High-frequency changing in voltage is dealt with a smaller capacitor, typically around 100 nF. Why decoupling capacitor placement in PCB matters? Ever wonder what would happen if you skipped decoupling capacitors in your design? I’ve done that for curiosity and here are a few signs to look out for. An onboard microcontroller will have trouble operating as the voltage fluctuation can send it into brownout mode where it gets reset. Any attempts to get reliable ADC conversion will be futile, as the analog voltage supply is anything but stable. If you’re to send a PCB board that has no decoupling capacitors installed to the field, you’ll have weirder problems due to the greater electrical noises. So, does placing a few decoupling capacitors on the PCB solve the problems? It depends. The placement of decoupling capacitors is crucial to mitigating voltage fluctuations. If you’re not placing the capacitors at the right place, the effect will be minimal at best. In some cases, the wrong placement of decoupling capacitors can be a problem by itself, as it could pick up EMI coupled onto the copper trace. Where to place decoupling capacitor placement in PCB? Unlike finding the best spot for a modern vase, placing decoupling capacitors is easier. The golden rule of decoupling capacitor placement is to minimize the distance between the component’s voltage pin and the capacitor. This means you’ll need to place the decoupling capacitor as close as possible to the IC’s pin. If you’re designing a multilayer PCB, place the capacitor beneath the component’s pad. On a single-layer design, the capacitor is placed near to the pin and routed with a short trace. As mentioned, you’ll need a 10uF and a 100 nF capacitor to stabilize against low and high-frequency fluctuations. The 100 nF capacitor should be placed closest to the voltage pin followed by the 10 uF capacitor. Repeat the process for as many VDD pin on the IC. There are some cases where the lack of space prevents the 1 decoupling capacitor per pin principle. In such instances, you’ll still need a minimum of 1 decoupling capacitor per component. · Place the capacitor near the signal source: Decoupling capacitors should be placed as close as possible to the source for decoupling the signal. This means the caps should be placed on the pin for ICs and near the connector for I/O signals. · Connect capacitor in series for I/O signal traces: To remove low-frequency transients from input and output signals, the capacitor should be connected in series with the trace. High-frequency will pass through the capacitor, but low-frequency and DC will be blocked. Additionally, small caps should be used for high-frequency transients and large caps for low-frequency transients. · Put the capacitor in parallel for power pins and grounds: Decoupling the I/O signal paths and power distribution and grounding is not that important, but the elimination of AC or coupling of DC is critical. Therefore, the capacitor should be connected in parallel with the signal path. · To minimize high-frequency EMI, connect a capacitor in parallel with a resistor: Decoupling capacitors can also be connected in parallel with resistors to filter out unwanted HF while allowing LF and DC to flow through. · Connect the capacitor before the ground plane connection: Connect the capacitor to the component pin before connecting it to the via to reach the power plane. This ensures smooth current flow through the plane. · Place the capacitor on the same layer as the digital and analog ground pours: Decoupling capacitors can also be used to separate analog and digital signals. This is accomplished by connecting a capacitor between AC and digital PCB ground pours.

PCB Knowledge ⋅ 08/12/2021 17:03

How to Choose Components for PCB？

During the PCB assembly process, components are very important to affect the performance and quality of the finished boards. How to choose components for PCB? In this article, we will focus on the topic, if you are curious about the methods please check and read the content we provide to learn more knowledge. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } What are the main factors before choosing components for PCB？ Performance and Design Requirements PCB components must be selected keeping in mind the design and performance requirements of the individual circuit. The components play an essential role in enabling the PCB board to perform its intended function. Therefore, the person selecting the components must understand the exact functions of the PCB board that is being designed. Once the engineer understands the intricacies and functionalities of the particular design, they can choose the right PCB components to bring that design into fruition. Technological Innovations and Advancements The latest advancements in web-based technology have made the task of component selection much easier. Smart digital tools for electronic component selection can be used by modern engineers to choose the perfect components for each PCB design. These web-based tools allow engineers to save time and money when selecting the PCB components. They can just check the online inventories of component manufacturers and select the components that they need for a particular design. Market Rates and Value Analysis An experienced engineer, who has a thorough understanding of PCB electronics will be able to accurately gauge the effectiveness of a specific PCB component vis-a-vis its market value. The engineer must also compare the price of a component to that of local products that are similar in design, or different versions of the same component. This will allow the engineer to choose the component that provides the best value for money and cost efficiency, allowing the business to gain a competitive edge over other companies operating in the field. Durability and Longevity One of the most important factors that must be taken into account when selecting PCB components is the quality and longevity of the product. High-quality and durable components are always more beneficial and cost-effective in the long run, even when they are slightly more expensive at the time of purchase. A PCB board made from high-quality components will be more durable and require fewer repairs over the course of its life. For instance, using circuit breakers instead of fuses and software control instead of manual switches can dramatically increase the longevity of a circuit. Furthermore, high-quality and properly sized dissipative devices such as resistors, inductors, and semiconductors ensure that the internal temperature of the circuit board always stays within reasonable limits. Guidelines of choosing components for PCB Think about Component Footprint Decisions Throughout the schematic drawing phase, consider footprint and landpattern decisions that will need to be made in the layout phase. See the following suggestions for things to consider when making component choices based on part footprints. Remember that footprints include both the electrical pad connections and the mechanical (X, Y and Z) dimensions of the part. This includes the body outline of the part as well as the pins that attach to the PCB. When selecting components, consider any housing or packing restrictions on both top and bottom sides of the final PCB. Some components (such as polarized capacitors) may have height clearance restrictions that need to be considered as part of the component selection process. When initially starting a PCB design, consider drawing a basic board outline shape and placing some of the larger or critically-placed components (such as connectors) that are planned to be used. In this way, a quick virtual rendering of the board (without routing) can be visualized to give a relatively accurate representation of the relative positioning and component heights of the board and components. This will assist in ensuring that the parts will fit inside the packaging (plastic, chassis, mechanical frame, etc…) after the PCB is assembled. Invoke the 3-D Preview mode from the tool menu to review your board. Landpatterns show the exact pads or hole shapes on the PCB to which the part will be soldered. These copper patterns on the PCB may also contain some basic shape information. The landpatterns need to be sized correctly to ensure proper soldering and to ensure proper mechanical and thermal integrity of the connecting parts. When designing the PCB layout consider how the board will be manufactured or if hand soldered, how the pads will be accessed. Reflow soldering (solder paste that is melted in a controlled oven) can handle a wide variety of surface mount devices (SMDs). Wave soldering is typically used to solder the backside of the board to fix through-hole components but can handle some SMD parts placed on the backside. Often with this technique, any bottom side SMDs will have to be orientated in a special direction and may to have pad modifications to be able to be soldered in this way. Component choices can change throughout the design process. Choosing which parts should be Plated Through Hole (PTH) or Surface Mount Technology (SMT) early in the design process can assist the entire planning of the PCB. Consider parts costs, availability, part area density and power dissipation among other things. From a manufacturing perspective SMD components are typically less expensive than through-hole parts and are typically more readily available. For small to medium prototyping projects, larger SMDs or through-hole parts may be preferred to facilitate hand soldering and to facilitate better pad and signal access for troubleshooting and debugging steps. Use Good Grounding Practices Make sure the design has sufficient bypass capacitors and ground planes. When using ICs, make sure appropriate decoupling capacitors are used near the supply to a ground location (ground plane preferably). Appropriately sized capacitors depend on the application, the capacitor technology and the frequencies involved. When bypass capacitors are placed across the power and ground pins and located close to the appropriate IC pins, a circuit’s electromagnetic compliance and susceptibility performance will be optimized. Assign Virtual Parts Footprints Run a bill of materials (BOM) to check for virtual parts. Virtual parts do not have footprints associated with them and will not be transferred to layout. Generate a BOM and review all the virtual components on the design. The only entries should be power and ground signals as these are considered virtual parts and are specially handled in the schematic environment and not the layout. Unless used solely for simulation purposes, parts that are shown in the virtual section should be replaced with parts having footprints. Ensure You Have Complete BOM Data Check for adequate data in the BOM report. After running the BOM report, review it and work on populating any incomplete part, vendor or manufacturer information for all of these parts. Sort Reference Designators To assist in the sorting and reviewing of the BOM, ensure reference designators are contiguously numbered. Check Spare Gates Typically, all of the spare gates should have the inputs connected to a signal to prevent the inputs from floating. Make sure you review any spare or forgotten gates so that unwired inputs can be adequately connected, if required. In some cases, if the inputs are left to float, the whole system may not function properly. For example, consider a dual opamp used in a design. If only a single opamp is used in a dual-section IC part, it is suggested that either a single-section IC be designed-in or for the unused portions, a ground be placed at the input and an appropriate unity gain (or otherwise) feedback network be placed with the amplifier to ensure the correct functionality of the part.

PCB Knowledge ⋅ 08/11/2021 17:08

Solder mask matte VS glossy

As a very essential step of PCB manufacturing process, solder mask. Most fabricators will likely default to a gloss surface finish, the more popular choice of the two. How to choose matte or glossy solder mask for your boards? Please check and read the content we provide to learn more information. PCB Instant Quote .my-button { display: inline-block; padding: 10px 50px; font-size: 16px; text-align: center; text-decoration: none; background-color: blue; color: #fffff0; border: none; border-radius: 5px; font-weight: bold; cursor: pointer; box-shadow: 0px 2px 5px rgba(0, 0, 0, 0.3); transition: background-color 0.3s ease, transform 0.3s ease; } .my-button:hover { background-color: #C23C30; transform: scale(1.05); } What are the advantages of matte solder mask & glossy solder mask? Matte solder mask Your preferences in PCB appearance will also determine whether you’ll want a matte finish instead of a glossy solder mask. A matte finish may make some aspects of fabrication easier. However, an experienced PCB company will provide quality results regardless of solder mask finish. The potential advantages of a matte finish include: · Visibility during inspection: A matte finish does not have shine under any lighting used during inspection. As a result, you can more easily see the PCB’s details. · Problem detection: Matte finishes make problems more evident than glossy finishes. During inspection, it becomes easier to detect issues on a matte finish due to increased visibility. · Solder ball reduction: Research suggests that matte finishes reduce a PCB’s risk of solder ball formation. Data indicates that a lower gloss level on PCBs results in lower solder ball levels. Glossy solder mask Many of the benefits of a solder mask finish depend on the customer’s aesthetic preferences. You might choose a glossy finish over a matte solder mask due to: · Aesthetic value: Because of glossy finishes’ role as the default choice for solder masks, many customers consider them the classic PCB appearance. Their shine gives them what many perceive as a more modern look. · Appearance of wear: The reflective properties of a glossy finish tend to make signs of wear look less prominent. · Scratch resistance: Because of its harder surface, a glossy finish has higher scratch resistance than a matte finish. Why to choose glossy finish than matte finish? The main difference between a gloss finish and a matte finish is an aesthetic one, and many people feel that a gloss finish simply looks better. Gloss solder masks are shiny. They reflect light and look lighter, while matte finishes are dull and dark. Gloss solder mask has a hard shell finish while a matte finish is softer looking. Matte finishes may also scratch more easily and show residue or surface cosmetics better, although scratches on a gloss finish will show more. If you expect the look of your PCB will have a positive effect on your assemblers or anyone who may end up looking at them, you may want to go with the gloss finish. Just keep in mind that the high light reflectivity can be a nuisance to vision during assembly in some cases. As a PCB customer, you may want to choose a glossy finish over a matte finish when: · Appearance matters for your PCB: In applications where appearance impacts your PCB marketing, a glossy finish can help by increasing aesthetic appeal. · You have no specific preference: If you don’t have a particular finish preference, remember that glossy finishes serve as the industry default for most suppliers. Why to choose matte finish than glossy finish? Although it is no more cost-effective or efficient to choose a matte finish over a glossy one, there is one consideration that may cause some to prefer the matte finish, and it involves solder balls. If you are concerned that solder balls may be a problem for you, you may be inclined to choose a matte finish. This is because, while there are several factors that contribute to solder balls, one is the level of surface roughness. The smoother the surface, the more likely it is that solder will ball up. The theory behind this is that molten solder behaves differently on rough surfaces and smooth surfaces. On rough surfaces, it tends to form a convex shape, reducing the area solder balls can attach to, while on smoother surfaces it tends to take a concave shape. Since matte finishes are softer and more porous, as opposed to the smooth, hard shell of the glossy finish, many experts feel that a matte finish will result in fewer solder balls. With all of this said, glossy finishes are used all the time on PCBs, so you may not find this to be a particular problem. When you’re considering your choice of solder mask finish, you might prefer a matte option in these situations: · You want to streamline production as much as possible: When you consider production accuracy a top priority, a matte finish may give you more peace of mind during fabrication. However, skilled PCB companies should detect errors in either finish type. · Participation in quality assurance matters to you: If you plan to inspect your PCB yourself after production, a matte finish can help with the process. It shows errors more clearly for you to provide accurate feedback to your PCB manufacturer.

PCB Knowledge ⋅ 08/10/2021 17:26